Muscle-Bound Cattle Reveal Meaty Mutation

Article excerpt

In their quests to beef up, Popeye ate spinach and Arnold Schwarzenegger pumped iron. Scientists have now found that some muscle-bound cattle, such as a hulking strain prized for its tender meat, acquire their brawn more easily: They have mutations in a gene that normally curtails muscle growth.

The story of this newfound gene started with some unexpectedly muscular mice and may end, researchers speculate, with the creation of meatier cattle, chickens, and pigs--and even with treatments for muscular dystrophies.

The gene prompting such hopes encodes myostatin, one of a large family of growth-regulating proteins. While looking for new members of that family, Se-Jin Lee of the Johns Hopkins Medical Institutions in Baltimore and his colleagues unearthed myostatin and found that it is made in mouse skeletal muscle.

The scientists then created a mouse strain with a deactivated myostatin gene. The mice develop into lumbering rodents, with two to three times more skeletal muscle mass than normal. "Picture a big grizzly bear walking on all fours," says Alexandra C. McPherron, a colleague of Lee.

Lee and McPherron, as well as two other research groups, have now identified mutations in the myostatin gene of the Belgian Blue, a celebrated strain of cattle bred in Belgium over the last few decades. Fed normally, Belgian Blues develop 20 to 30 percent more muscle than average cattle, and their meat is lower in fat and unusually tender.

In the September Nature Genetics, a European team led by Michel Georges of the University of Liege in Belgium reports that the animals are missing a small portion of their myostatin gene; the group had sought a mutation in Belgian Blues for more than a decade. …